Selected Materials on the Calvert Cliffs Decision, Its Origin and Aftermath

3.1 Equipment leakage or malfunction (includes operator error). (a) Radioactive gases and liquids: 25 percent of average inventory in the largest storage tank shall be assumed to be released.

(b) Meteorology assumptions-x/Q values are to be 10 of those given in AEC Safety Guide No. 3 or 4.2

(c) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction. 3.2 Release of waste gas storage tank contents (includes failure of release valve and rupture disks).

(a) 100 percent of the average tank inventory shall be assumed to be released.

(b) Meteorology assumptions-x/Q values shall be 10 of those given in AEC Safety Guide No. 3 or 4.

(c) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction. 3.3 Release of liquid waste storage tank contents.

(a) Radioactive liquids-100 percent of the average storage tank inventory shall be assumed to be spilled on the floor of the building. (b) Building structure shall be assumed to remain intact.

(d) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction.

ACCIDENT 4.0 FISSION PRODUCTS TO PRIMARY SYSTEM (BWR)

4.1 Fuel cladding defects.

Releases from these events shall be included and evaluated under routine releases in accordance with proposed Appendix I.

4.2 Off-design transients that induce fuel failures above those expected (such as flow blockage and flux maldistributions).

(a) 0.02 percent of the core inventory of noble gases and 0.02 percent of the core inventory of halogens shall be assumed to be released into the reactor coolant.

(b) 1 percent of the halogens in the reactor coolant shall be assumed to be released into the steam.

(c) The mechanical vacuum pump shall be assumed to be automatically isolated by a high radiation signal on the steamline.

(d) Radioactivity shall be assumed to carry over to the condenser where 10 percent of the halogens shall be assumed to be available for leakage from the condenser to the environment at 0.5 percent/day for the course of the accident (24 hours).

(e) Meteorology assumptions-x/Q values shall be 10 of those given in AEC Safety Guide No. 3 dated November 2, 1970.

(f) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction.

2 Copies of such Guide (s), dated Nov. 2, 1970, are available at the Commission's Public Document Room, 1717 H Street NW., Washington, DC, and on request to the Director, Division of Reactor Standards, U.S. Atomic Energy Commission, Washington, D.C. 20545.

ACCIDENT—5.0 FISSION PRODUCTS TO PRIMARY AND SECONDARY SYSTEMS

(PRESSURIZED WATER REACTOR)

5.1 Fuel cladding defects and steam generator leak.

Releases from these events shall be included and evaluated under routine releases in accordance with proposed Appendix I.

5.2 Off-design transients that induce fuel failure above those expected and steam generator leak (such as flow blockage and flux maldistributions).

(a) 0.02 percent of the core inventory of noble gases and 0.02 percent of the core inventory of halogens shall be assumed to be released into the reactor coolant.

(b) Average inventory in the primary system prior to the transient shall be based on operation with 0.5 percent failed fuel.

(c) Secondary system equilibrium radioactivity prior to the transient shall be based on a 20 gal./day steam generator leak and a 10 g.p.m. blowdown rate.

(d) All noble gases and 0.1 percent of the halogens in the steam reaching the condenser shall be assumed to be released by the condenser air ejector.

(f) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction. 5.3 Steam generator tube rupture.

(a) 15 percent of the average inventory of noble gases and halogens in the primary coolant shall be assumed to be released into the secondary coolant.

The average primary coolant activity shall be based on 0.5 percent failed fuel.

(b) Equilibrium radioactivity prior to rupture shall be based on a 20 gallon per day steam generator leak and a 10 g.p.m. blowdown rate.

(c) All noble gases and 0.1 percent of the halogens in the steam reaching the condenser shall be assumed to be released by the condenser air ejector.

(d) Meteorology assumptions-x/Q. values shall be 10 of those given in AEC Safety Guide No. 4.

(e) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction.

ACCIDENT-6.0

6.1 Fuel bundle drop.

REFUELING ACCIDENTS

(a) The gap activity (noble gases and halogens) in one row of fuel pins shall be assumed to be released into the water. (Gap activity is 1 percent of total activity in a pin.)

(b) One week decay time before the accident occurs shall be assumed.

(d) Charcoal filter efficiency for iodines shall be 99 percent. (e) A realistic fraction of the containment volume shall be assumed to leak to the atmosphere prior to isolating the containment.

(f) Meteorology assumptions-x/Q values shall be 10 of those given in AEC Safety Guide No. 3 or 4.

(g) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction. 6.2 Heavy object drop onto fuel in core.

(a) The gap activity (noble gases and halogens) in one average fuel assembly shall be assumed to be released into the water. (Gap activity shall be 1 percent of total activity in a pin.)

(b) 100 hours of decay time before object is dropped shall be assumed.

(d) Charcoal filter efficiency for iodines shall be 99 percent. (e) A realistic fraction of the containment volume shall be assumed to leak to the atmosphere prior to isolating the containment.

(f) Meteorology assumptions x/Q values shall be 10 of those given in AEC Safety Guide No. 3 or 4.

(g) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction.

ACCIDENT-7.0 SPENT FUEL HANDLING ACCIDENT

7.1 Fuel assembly drop in fuel storage pool.

(a) The gap activity (noble gases and halogens) in one row of fuel pins shall be assumed to be released into the water. (Gap activity shall be 1 percent of total activity in a pin.)

(b) One week decay time before the accident occurs shall be assumed.

(e) Meteorology assumptions-x/Q values shall be 10 of those given in AEC Safety Guide No. 3 or 4.

(f) Consequences shall be calculated by weighting the effects in different directions by the frequency the wind blows in each direction. 7.3 Heavy object drop onto fuelrack.

(a) The gap activity (noble gases and halogens) in one average fuel assembly shall be assumed to be released into the water. (Gap activity is 1 percent of total activity in a pin).

(b) 30 days decay time before the accident ocurs shall be assumed. (c) Iodine decontamination factor in water shall be 500. (d) Charcoal filter efficiency for iodines shall be 99 percent.

(e) Meteorology assumptions-x/Q values shall be 10 of those given in AEC Safety Guide No. 3 or 4.

(f) Consequences shall be calculated by weighting the effects in different directions by the frequency the wind blows in each direction. 7.3 Fuel cask drop.

(a) Noble gas gap activity from one fully loaded fuel cask (120 day cooling) shall be assumed to be released. (Gap activity shall be 1 percent of total activity in the pins).

(b) Meteorology assumptions-x/Q values shall be 10 of those given in AEC Safety Guide No. 3 or 4.

(c) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction.

ACCIDENT-8.0 ACCIDENT INITIATION EVENTS CONSIDERED IN DESIGN BASIS EVALUATION IN THE SAFETY ANALYSIS REPORT

8.1 Loss-of-coolant accidents.

Small pipe break (6′′ or less)

(a) Source term-The average radioactivity inventory in the primary coolant be assumed (This inventory shall be based on operation with 0.5 percent failed fuel).

(b) Filter efficiencies shall be 95 percent for internal filters and 99 percent for external filters.

assumed.

(d) For the effects of Plateout, Sprays, Decontamination Factor in Pool, and Core Sprays the following reduction factors shall be

assumed :

For pressurized water reactors-0.05 with chemical additives in sprays, 0.2 for no chemical additives.

For boiling water reactors-0.2.

(e) A realistic building leak rate as a function of time shall be assumed.

(f) Meteorology Assumptions-x/Q values shall be 10 of those in AEC Safety Guide No. 3 or 4.

(g) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction.

Large pipe break

(a) Source term--The average radioactivity inventory in the primary coolant shall be assumed (This inventory shall be based on operation with 0.5 percent failed fuel), plus release into the coolant of: For pressurized water reactors-2 percent of the core inventory of halogens and noble gases.

For boiling water reactors-0.2 percent of the core inventory of halogens and noble gases.

(b) Filter efficiencies shall be 95 percent for internal filters and 99 percent for external filters.

(d) For the effects of Plateout. Containment Sprays, Core Sprays (values based on 0.5 percent of halogens in organic form) the following reduction factors shall be assumed:

For pressurized water reactors-0.05 with chemical additives in sprays, 0.2 for no chemical additives.

For boiling water reactors-0.2.

(e) A realistic building leak as a function of time and including leakage of steamline valves in BWRS shall be assumed.

()f Meteorology Assumptions-x/Q values shall be 1/10 of those gicen in AEC Safety Guide No. 3 or 4.

(g) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction.

8.1(a) Break in instrument line from primary system that penetrates the containment (lines not provided with isolation capability inside containment).

(a) The primary coolant inventory of noble gases and halogens shall be based on operation with 0.5 percent failed fuel.

(b) Release rate through failed line shall be assumed constant for the four hour duration of the accident,

(d) Reduction factor from combined plateout and building mixing shall be 0.1.

(e) Meteorology assumptions-x/Q values shall be 10 of those given in AEC Safety Guide No. 3.

(f) Consequences shall be calculated by weighting the effects in different directions by the frequency the wind blows in each direction. 8.2(a) Rod ejection accident (pressurized water reactor).

(a) 0.2 percent of the core inventory of noble gases and halogens shall be assumed to be released into the primary coolant plus the average inventory in the primary coolant based on operation with 0.5 percent failed fuel.

(b) Loss-of-coolant accident occurs with break size equivalent to diameter of rod housing. (See assumption for Accident 8.1). 8.2(b) Rod drop accident (boiling water reactor).

Radioactive material released.

(a) 0.025 percent of the core inventory of noble gases and 0.025 percent of the core inventory of halogens shall be assumed to be released into the coolant.

(b) 1 percent of the halogens in the reactor coolant shall be assumed to be released into the condenser.

(e) Meeteorology assumptions-x/Q values shall be 10 of those given in AEC Safety Guide No. 3.

(f) Consequences should be calculated by weighting the effects in different directions by the frequency the wind blows in each direction. 8.3(a) Steamline breaks (pressurized water reactors-outside containment). Break size equal to area of safety valve throat.

Small break

(a) Primary coolant activity shall be based on operation with 0.5 percent failed fuel. The primary system contribution during the course of the accident shall be based on a 20 gal./day tube leak.

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